Exploits in Python - manipulating hex strings

Question

I'm quite new to python and trying to port a simple exploit I've written for a stack overflow (just a nop sled, shell code and return address). This isn't for nefarious purposes but rather for a security lecture at a university.

Given a hex string (deadbeef), what are the best ways to:

• represent it as a series of bytes
• add or subtract a value
• reverse the order (for x86 memory layout, i.e. efbeadde)

Any tips and tricks regarding common tasks in exploit writing in python are also greatly appreciated.